Management of Acute Pain in Patients on Methadone

General Principles

• The American College of Physicians recommends continuing the patient's usual dose of methadone and adding short-acting opioids at higher doses and more frequent intervals than for non-tolerant patients 1, 2
• Reassure the patient that their maintenance treatment will not be interrupted and that their pain will be adequately treated 1
• Avoid using mixed agonist-antagonists (pentazocine, nalbuphine, butorphanol) as they may precipitate withdrawal syndrome 2

Analgesic Strategy

• Use short-acting opioids (morphine, hydromorphone, oxycodone) in addition to the daily dose of methadone 1, 2
• Prescribe analgesics at fixed intervals rather than on demand 1

Pharmacological Considerations

• Avoid using fixed-dose combination products containing acetaminophen for patients requiring high doses of opioids (risk of hepatotoxicity) 2

Multimodal Approach

• Use non-opioid analgesics (NSAIDs, acetaminophen) in combination 3
• Consider adjuvant analgesics that potentiate the effect of opioids (tricyclic antidepressants) 3
• Patient-controlled analgesia (PCA) may be considered for hospitalized patients to minimize anxiety related to pain management 2

Monitoring and Precautions

• Frequently monitor the level of consciousness and respiratory rate 1, 4
• Have naloxone available in case of respiratory depression 4
• Inform the methadone clinic or prescribing physician of the patient's admission, discharge, and medications administered 1

Pitfalls to Avoid

• Under-treat pain due to fear of addiction or diversion ("opiophobie") 5, 3
• Confuse analgesic-seeking behavior with addiction 3
• Allow pain to recur before administering the next dose, causing unnecessary suffering and increasing tension between the patient and healthcare team 3

Methadone Patients with Acute Pain Management

Dosing Strategies

• When splitting the daily methadone dose into 6-8 hour intervals to leverage its analgesic properties, it's recommended to add 5-10% of the current methadone dose for afternoon and evening doses, resulting in a 10-20% increase compared to the regular maintenance dose. 6

Pharmacological Considerations

• Methadone has a long and unpredictable half-life, but its analgesic effect is shorter (6-8 hours) than its effect on opioid dependence. 7

Management of Acute Pain in Patients on Methadone

General Principles

• The American College of Physicians recommends continuing the patient's usual daily dose of methadone without interruption, while adding rapid-acting opioids (such as morphine) to treat acute pain, as patients on methadone may require higher doses and more frequent administration due to cross-tolerance to other opioids 8

Dose Adjustment

• The European Society for Medical Oncology recommends rapidly titrating the dose to achieve adequate pain relief, with rescue doses equivalent to 10-15% of the total daily dose for breakthrough pain, and increasing the base dose if more than four rescue doses are needed per day 9

Pain Control for Acute Pain and Narcotic Withdrawal

General Principles

• For patients on opioid agonist therapy, the American College of Physicians recommends continuing their maintenance dose without interruption and adding scheduled short-acting opioids at higher doses and shorter intervals than used for opioid-naïve patients, combined with aggressive multimodal non-opioid analgesia 10
• The American College of Physicians suggests that patients will require higher doses at shorter intervals (every 3-4 hours) due to cross-tolerance 10
• It is recommended to verify the maintenance dose with the patient's clinic or prescribing physician before initiating treatment, as stated by the American College of Physicians 10
• The American College of Physicians advises to notify the methadone clinic about hospitalization and any controlled substances prescribed 10
• The American College of Physicians recommends continuing buprenorphine at the current dose and adding short-acting full opioid agonists at higher-than-usual doses with scheduled dosing 10
• The American College of Physicians suggests that temporarily discontinuing buprenorphine and using full opioid agonists, then converting back when acute pain resolves, may be considered for severe acute pain 10
• The American College of Physicians recommends notifying the buprenorphine prescriber about additional opioids prescribed, as they will appear on urine drug screening 10
• Explicitly reassuring patients that their addiction history will not prevent adequate pain management and that maintenance therapy will continue is crucial, as stated by the American College of Physicians 10
• The American College of Physicians advises to verify maintenance doses with the patient's clinic or prescribing physician and inform them about admission, discharge, and any controlled substances prescribed 10
• The American College of Physicians suggests that pseudoaddiction should not be confused with true addiction, as drug-seeking behaviors may represent legitimate attempts to obtain relief from uncontrolled pain 10
• Therapeutic dependence (fear of pain or withdrawal reemergence) is a normal response, not addiction, according to the American College of Physicians 10
• The American College of Physicians recommends not using as-needed dosing, but instead writing continuous scheduled orders 10
• The American College of Physicians advises against using mixed agonist-antagonists, such as pentazocine, nalbuphine, or butorphanol, as they will precipitate acute withdrawal syndrome 10

Rescue Pain Management in Opioid-Tolerant Patients

Introduction to Rescue Dosing

• The American Society of Clinical Oncology recommends using immediate-release oral morphine as rescue medication, dosed at 10-20% of the total 24-hour opioid equivalent, administered every hour as needed for breakthrough pain in opioid-tolerant patients 11, 12

Calculating the Rescue Dose

• The National Comprehensive Cancer Network recommends calculating the total 24-hour opioid requirement by converting all current opioids to oral morphine equivalents, to determine the rescue dose 12, 13
• The rescue dose should be 10-20% of the total daily dose, according to the European Society for Medical Oncology 11, 12

Route and Formulation Selection

• The European Society for Medical Oncology recommends using immediate-release (IR) oral morphine as the preferred rescue medication because it must be used to treat exacerbations of controlled background pain 11, 14, 15
• The oral route should be used as first choice, unless the patient cannot swallow, as suggested by the British Journal of Anaesthesia 11, 16

Reassessment and Dose Adjustment

• The National Comprehensive Cancer Network recommends assessing efficacy and adverse effects every 60 minutes after oral administration, and adjusting the dose accordingly 12, 13
• If pain score remains unchanged or increases after the first rescue dose, administer 50-100% of the previous rescue dose, as recommended by the National Comprehensive Cancer Network 12, 13

Adjusting Baseline Therapy

• The European Society for Medical Oncology recommends calculating the total rescue medication used in 24 hours and adding this to the baseline regimen, to adjust the baseline long-acting opioid dose 11, 14, 15

Critical Consideration: Thrombocytopenia

• The European Society for Medical Oncology recommends exercising caution with NSAIDs given the thrombocytopenia, as these increase bleeding risk, and considering acetaminophen as a safer alternative for adjunctive analgesia 14, 15

Monitoring Requirements

• The British Journal of Anaesthesia recommends monitoring sedation scores and respiratory rate to detect opioid-induced ventilatory impairment 16
• The European Society for Medical Oncology recommends maintaining prophylactic laxatives for opioid-induced constipation 11, 14, 15